Role of F-FDG PET/CT in patients affected by Langerhans cell histiocytosis.

PURPOSE

Langerhans cell histiocytosis (LCH) is a rare hematological disorder for which the utility ofF-FDG PET/CT is unclear. Our aim was to explore the metabolic features of LCH and the possible role ofF-FDG PET/CT in LCH evaluation.

MATERIALS AND METHODS

We found 17 patients with histologically proven LCH who underwent 17F-FDG PET/CT scans for staging and 42 scans for restaging/follow-up purposes. PET/CT results were compared with those obtained from other conventional imaging modalities (bone scintigraphy, plain radiogram, computed tomography, magnetic resonance).

RESULTS

F-FDG PET/CT was positive in 15/17 patients, and it detected 36/37 lesions; all bone and extraskeletal lesions, except for a cecal lesion, wereF-FDG-avid. Only 1/4 of the patients with lung LCH had hypermetabolic lesions. The average SUV of the FDG-avid lesions was 7.3 ± 6.7, the average lesion-to-liver SUV ratio was 3.4 ± 2.5, and the average lesion-to-blood pool SUV ratio was 4 ± 3.2. In comparison to other imaging methods,F-FDG PET/CT detected additional lesions or was able to evaluate treatment response earlier in 33/74 cases; it was confirmatory in 38/74 and detected fewer lesions in 3/74 (all three with lung LCH).

CONCLUSIONS

F-FDG PET/CT seems to be useful for evaluating LCH when compared to conventional imaging, except in pulmonary cases. It can be used both for staging and restaging purposes.